This pair of Lasting Sport SWC socks, from the 2000s, are designed for wearing when skiing. They are made from 50% Thermolite (R), a form of polyester. Thermolite (R) is a hollow polyester fibre which provides warmth without weight. The hollow centre acts as a capillary, helping to wick away any moisture that would otherwise act as a conductor of built-up heat. It is also resistant to mildew and odour retention.